When performing distributed builds of machine learning packages, it
would be nice if builders without the required SIMD instructions can
be excluded as build nodes.
Since x86_64 has accumulated a large number of different instruction
set extensions, listing all possible extensions would be unwieldy.
AMD, Intel, Red Hat, and SUSE have recently defined four different
microarchitecture levels that are now part of the x86-64 psABI
supplement and will be used in glibc 2.33:
https://gitlab.com/x86-psABIs/x86-64-ABIhttps://lwn.net/Articles/844831/
This change uses libcpuid to detect CPU features and then uses them to
add the supported x86_64 levels to the additional system types. For
example on a Ryzen 3700X:
$ ~/aps/bin/nix -vv --version | grep "Additional system"
Additional system types: i686-linux, x86_64-v1-linux, x86_64-v2-linux, x86_64-v3-linux
Our use of boost::coroutine2 depends on -lboost_context,
which in turn depends on `-lboost_thread`, which in turn depends
on `-lboost_system`.
I suspect that this builds on nix only because of low-level hacks
like NIX_LDFLAGS.
This commit passes the proper linker flags, thus fixing bootstrap
builds on non-nix distributions like Ubuntu 16.04.
With these changes, I can build Nix on Ubuntu 16.04 using:
./bootstrap.sh
./configure --prefix=$HOME/editline-prefix \
--disable-doc-gen \
CXX=g++-7 \
--with-boost=$HOME/boost-prefix \
EDITLINE_CFLAGS=-I$HOME/editline-prefix/include \
EDITLINE_LIBS=-leditline \
LDFLAGS=-L$HOME/editline-prefix/lib
make
where
* g++-7 comes from gcc-7 from
https://launchpad.net/~ubuntu-toolchain-r/+archive/ubuntu/test,
* editline 1.14 from https://github.com/troglobit/editline/releases/tag/1.14.0
was installed into `$HOME/editline-prefix`
(because Ubuntu 16.04's `editline` is too old to have the function nix uses),
* boost 1.66 from
https://www.boost.org/doc/libs/1_66_0/more/getting_started/unix-variants.html
was installed into $HOME/boost-prefix (because Ubuntu 16.04 only has 1.58)
That was incorrect, because checking the dirent type already requires
a working compiler.
It had the effect that setting e.g. `: ${CFLAGS=""}` before `AC_PROG_CC`
as per `AC_PROG_CC`'s documentation would have no effect, because
`AC_STRUCT_DIRENT_D_TYPE` would automatically set CFLASGS.
(In a followup commit `: ${CFLAGS=""}` will be used, so it's important
to get this working first.)
And probably many other distributions.
Until now, ./configure would fail silently printing a warning
./configure: line 4621: AX_CXX_COMPILE_STDCXX_17: command not found
and then continuing, later failing with a C++ #error saying that some C++11
feature isn't supported (it didn't even get to the C++17 features).
This is because older distributions don't come with the
`AX_CXX_COMPILE_STDCXX_17` m4 macro.
This commit vendors that macro accordingly.
Now ./configure complains correctly:
configure: error: *** A compiler with support for C++17 language features is required.
On Ubuntu 16.04, ./configure completes if a newer compiler is used, e.g. with
gcc-7 from https://launchpad.net/~ubuntu-toolchain-r/+archive/ubuntu/test
using:
./bootstrap.sh
./configure CXX=g++-7 --disable-doc-gen --with-boost=$(nix-build --no-link '<nixpkgs>' -A boost.dev)
And probably other Linux distributions with long-term support releases.
Also update manual stating what version is needed;
I checked that 1.14 is the oldest version with which current nix compiles,
and added autoconf feature checks for some functions added in that release
that nix uses.
This turns previous compiler errors complaining about missing files
into proper ./configure time errors telling the user which version
of boost is required.
The unbalanced single-quotes cause many editor syntax highlighters
to interpret the rest of the file as a string literal, making it easier
to make syntax mistakes in absence of proper highlighting.
